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Date: Mon, 5 Feb 2018 19:29:57 +0100
From: Ingo Molnar <mingo@kernel.org>
To: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        Dan Williams <dan.j.williams@intel.com>,
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        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH 1/3] x86/entry: Clear extra registers beyond syscall
 arguments for 64bit kernels
Message-ID: <20180205182957.xbeufjgyhd7pgdvq@gmail.com>
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* Andy Lutomirski <luto@kernel.org> wrote:

> [...] Clearing R10 is mostly useless in the syscall path because we'll just 
> unconditionally reload it in do_syscall_64().

AFAICS do_syscall_64() doesn't touch R10 at all. So how does it reload R10?

In fact do_syscall_64() as a C function does not touch R10, R11, R12, R13, R14, 
R15 - it passes their values through.

What am I missing?

Thanks,

	Ingo